Hypericum sp.: essential oil composition and biological activities

Phytochemical composition of Hypericum genus has been investigated for many years. In the recent past, studies on the essential oils (EO) of this genus have been progressing and many of them have reported interesting biological activities. Variations in the EO composition of Hypericum species influenced by seasonal variation, geographic distribution, phenological cycle and type of the organ in which EO are produced and/or accumulated have also been reported. Although many reviews attributed to the characterization as well as biological activities of H. perforatum crude extracts have been published, no review has been published on the EO composition and biological activities of Hypericum species until recently (Crockett in Nat Prod Commun 5(9):1493–1506, 2010; Bertoli et al. in Global Sci Books 5:29–47, 2011). In this article, we summarize and update information regarding the composition and biological activities of Hypericum species EO. Based on experimental work carried out in our laboratory we also mention possible biotechnology approaches envisaging EO improvement of some species of the genus.Fundação para a Ciência e a Tecnologia (FCT) - project PTDC/AGR AAM/70418/2006, SFRH/BD/ 13283/2003

Magnesium and health outcomes: An umbrella review of systematic reviews and meta-analyses of observational and intervention studies

Purpose: To map and grade all health outcomes associated with Magnesium (Mg) intake using an umbrella review. Methods: Umbrella review of systematic reviews with meta-analyses of observational studies and randomised controlled trials (RCTs) using placebo/no intervention as control group. We assessed meta-analyses of observational studies based on random-effects summary effect sizes and their P-values, 95% prediction intervals, heterogeneity, small-study effects and excess significance. For meta-analyses of RCTs, outcomes with a random effects P-value <0.005 and a high GRADE assessment, were classified as strong evidence. Results: From 2,048 abstracts, 16 meta-analyses and 55 independent outcomes were included (36 in RCTs and 19 in observational studies). In RCTs of Mg versus placebo/no active treatment, 12 over 36 outcomes reported significant results (p<0.05). A strong evidence for decreased need for hospitalization in pregnancy and for decreased risk of frequency and intensity of migraine relapses in people with migraine was observed using the GRADE assessment. In observational studies, 9/19 outcomes were significant (p<0.05). However, only one outcome presented highly suggestive evidence (lower incidence of type 2 diabetes in people with higher Mg intake at baseline) and one suggestive (lower incidence of stroke associated with higher Mg intake at baseline). Conclusion: Strong evidence according to the GRADE suggests that Mg supplementation can decrease the risk of hospitalization in pregnant women and reduce the intensity/frequency of migraine. Higher Mg intake is associated with a decreased risk of type 2 diabetes and stroke with highly suggestive and suggestive evidence, respectively, in observational studies

Inefficient Vaginal Transmission of Tenofovir-Resistant HIV-1

Transmission of drug-resistant HIV has been postulated to be a threat to current first-line antiretroviral therapy (ART) regimens and the efficacy of several antiretroviral-based preexposure prophylaxis (PrEP) strategies being tested. Here we evaluated the effect of the common tenofovir (TFV) resistance mutation K65R on vaginal HIV transmission. Our results demonstrate that despite no overt loss of overall replication competence in vivo, this mutation results in significantly reduced mucosal transmission. When transmitted, the mutant virus eventually reverted to the wild type in 2 of 3 animals examined

PEGylation of native disulfide bonds in proteins

PEGylation has turned proteins into important new biopharmaceuticals. The fundamental problems with the existing approaches to PEGylation are inefficient conjugation and the formation of heterogeneous mixtures. This is because poly(ethylene glycol) (PEG) is usually conjugated to nucleophilic amine residues. Our PEGylation protocol solves these problems by exploiting the chemical reactivity of both of the sulfur atoms in the disulfide bond of many biologically relevant proteins. An accessible disulfide bond is mildly reduced to liberate the two cysteine sulfur atoms without disturbing the protein's tertiary structure. Site-specific PEGylation is achieved with a bis-thiol alkylating PEG reagent that sequentially undergoes conjugation to form a three-carbon bridge. The two sulfur atoms are re-linked with PEG selectively conjugated to the bridge. PEGylation of a protein can be completed in 24 h and purification of the PEG-protein conjugate in another 3 h. We have successfully applied this approach to PEGylation of cytokines, enzymes, antibody fragments and peptides, without destroying their tertiary structure or abolishing their biological activity.Peer reviewe